valve, tube, thermionic, electron, triode, tetrode, pentode, power,
magic eye, tuning indicator, nixie, history, data, data sheet,
specification, amplifier, radio, octal, B9A, B7G, B4, IO, KT88,
KT66, 12AX7, 12AY7, 12AT7, ECC81, ECC82, ECC83, 6L6, 6V6, EL34,
EL84, EM34, EM80, EM81, EM85, Mullard, Cossor, GEC, Gold Lion,
Marconi, Svetlana, Brimar, Ferranti, RCA, Sylvania, GE,
Mullard
This is a 1927-8 Mullard PM series box with BVA
markings and a 1927 patent. The boxes were made in various
colourways.